“It’s so hot, the hens are laying hard-boiled eggs” (Texas heat joke)

It’s often joked that it’s so hot in Texas, “the hens/chickens are laying hard-boiled eggs.” TheTexas version of the joke dates to at least 1953.
 
The “laying hard-boiled eggs” joke has been cited in print since at least 1860 and 1870, when it was told about the heat in California.
 
 
11 April 1860, Wisconsin Chief (Milwaukee and Fort Atkinson, WI), pg. 1, cols. 4-5:
OUR CALIFORNIA CORRESPONDENCE.
From the Evergreen City Times.
SACRAMENTO, Feb. 18, 1860.
(...)
If you have never been at Panama—or Purgatory—never been melted in a furnace, or read the California adventures of “old Block,” who gravely speaks of seeing “roasted chickens run about the streets laying hard boiled eggs,” of “cows giving sour milk at every milking,: of “hogs that faint away with the effort of smelling,” don’t for a moment suppose you have any conception of the heat.
   
30 July 1870, The Critic (Washington, DC), pg. 4, col. 4:
The hens out West are laying hard-boiled eggs this weather.
 
Chronicling America
10 August 1870, The Daily Phoenix (Columbia, SC), pg. 1, col. 1:
John Phoenix speaks of Fort Yuma, on the Colorado River, as being a place “where the thermometer stands at 212 degress in the shade, and the hens lay hard-boiled eggs.”
 
Chronicling America
29 July 1880, Red Cloud (Webster County, NE) Chief, pg. 4, col. 3:
It is reported to us that since the heated term commenced the hens have all begun laying hard boiled eggs.
 
Papers Past
28 October 1880, Thames (NZ) Star, pg. 2:
It has been so hot at Oakland, San Francisco, that one of the hens is laying hard-boiled eggs. This hen promises to be immortal, as her son can never set.—American Paper.
 
Google Books
September 1886, Travelers’ Record, pg. 6, col. 3:
The ducks which frequent a watercourse in the drouth section of the Mississippi have been laying hard-boiled eggs for the last three weeks.
 
Papers Past
8 January 1892, Mataura (NZ) Ensign, “Wit and Humour,” pg. 5:
“UNDER the equator, gentlemen, “remarked an extensice traveller, “it is so hot that the natives have to put the hens in ice-chests to prevent them laying hard-boiled eggs.”
   
Google Books 
March 1953, Boys’ Life, “Think and Grin,” pg. 74, col. 3:
Northerner: “The Maine winters are so cold, we have to put heaters under the cows so we can milk them.”
Southerner: “That’s nothing. The Texas summers are so hot, we have to feed the hens ice to keep them from laying hard boiled eggs.”— Gordon Spurgeon, Shellsburg, la.